1. Field of the Invention
The present invention relates to a recording and reproducing method for a dye-based recordable optical recording medium in which information can be recorded and reproduced by irradiating a dye-based recordable optical recording medium with a light beam to induce optical changes such as transmittance and reflectance to the recording layer thereof, and an apparatus for the recording and reproducing method.
2. Description of the Related Art
Recently, recordable digital versatile discs (DVD-R) have been developed for providing advanced large capacity optical discs. In order to enhance recording capacity of optical discs, it is necessary to develop recording materials to micronize recording pits, to adopt image compression formatting technologies as typified by MPEG2, and to develop technologies for shortening the wavelength of semiconductor lasers for reading recording pits.
Conventionally, as for semiconductor lasers of red wavelength regions, only AlGaInP laser diodes of a wavelength of 670 nm have been commercially utilized, for example, for barcode readers or instrumentation units. Nowadays, red lasers are remarkably expanding their markets in terms of optical storage products along with high-densification of optical discs. DVD drives are standardized at two wavelengths of 635 nm and 650 nm using laser diodes for their light sources, and DVD-ROM (Read Only Memory Digital Versatile Disc) drives of a wavelength of 650 nm are commercially available.
Typically, in dye-based recordable optical recording media where pits or marks are formed by use of heat mode, the pulse width and the recording power of a recording pulse train are optimized by emission of a laser during recording at a specific recording speed, thus there exist a problem that the marks and/or spaces are different at the other recording linear velocities. Namely, dye-based recordable optical recording media suffer from problems that jitter properties tend to degrade with time, because thermal capacity of heat pulses at the front edge required to form marks turns into insufficient, the heating temperatures are different from the optimal decomposing temperature, and thus average mark lengths are often varied, and the duty ratio of optimal heating pulse varies, mark widths are hardly uniform, and thus uniform mark widths cannot be obtained, resulting in thin marks or thick marks in accordance with mark lengths.
In addition, as for physical formats of DVD media, DVD-R media are standardized with a format of which the land portions of so-called land pre-pits are partially cut. According to the format, there are problems that when the land pre-pit signal (LPPb) is less than 0.16, pre-pit information such as pre-pit addresses cannot be properly reproduced; on the other hand, when the land pre-pit signal is more than 0.32, the land-pit signals themselves act noisily at data region, thus resulting in frequent occurrences of data errors. Accordingly, there is a disadvantage that the cut width should be adjusted with respect to each recording material by the use of a stamper, and the land cut width should be adjusted so as to control the land pre-pit signal within the range of 0.16 to 0.32.
In the prior art concerning optical recording media using a dye in the recording layer, there are optical recording media using polymethine dyes or combination of polymethine dyes and optical stabilizers as recording material; optical recording media using a layer formed from tetraazaporphyrin (porphyrazin) dye or a combination of cyanine dyes and azometalchelate dyes (salt forming dye) and a reflective layer as a recording layer; optical recording media using formazane (metal chelate) dye and the other dyes as the recording material; and optical recording media using dipyromethene (metal chelate) dye and the other dyes as the recording material. Further, there are many proposals known in the art which perform multi-pulse recording using dyes as the recording materials, however, as far as the inventors of the present invention know, there is no document found that one pulse recording is performed on dye-based recordable optical recording media while optimizing the recording waveform to perform recording at higher linear velocities, like the present invention.